Buffer Calculator

Calculate buffer pH using Henderson-Hasselbalch equation. Prepare common biological buffers with precise pH control for your experiments.

Common Buffer Systems

Buffer Parameters

Calculated Results

What is Buffer Calculator?

This calculator uses the Henderson-Hasselbalch equation to determine buffer pH based on pKa and the ratio of conjugate base to acid. Essential for preparing biological buffers with precise pH control for biochemical experiments, cell culture, and molecular biology applications.

How to Use This Calculator

Calculate buffer pH:

  1. Select a common buffer preset or use custom values
  2. Enter the pKa of your buffer system
  3. Input acid and base concentrations (M)
  4. Set temperature (affects pKa)
  5. Click "Calculate pH" to get results

Common Buffers

Popular biological buffer systems:

  • Tris-HCl: pKa 8.06 (25°C), pH 7.0-9.0
  • HEPES: pKa 7.55 (25°C), pH 6.8-8.2
  • MES: pKa 6.15 (25°C), pH 5.5-6.7
  • Phosphate: pKa 7.21 (25°C), pH 6.2-8.2
  • Acetate: pKa 4.76 (25°C), pH 3.6-5.6

Henderson-Hasselbalch Equation

The fundamental equation for buffer pH:

pH = pKa + log₁₀([A⁻]/[HA])

Where:
• [A⁻] = base concentration
• [HA] = acid concentration
• pKa = acid dissociation constant

Buffer Capacity

Effective buffering occurs when:

  • pH is within ±1 unit of pKa
  • Acid:base ratio is between 10:1 and 1:10
  • Total buffer concentration is adequate (typically 50-200 mM)
  • Optimal buffering at pH = pKa (1:1 ratio)

FAQ

Q: Why does temperature matter?
A: pKa values are temperature-dependent. Most pKa values decrease by ~0.03 units per 1°C increase.

Q: What's a good buffer concentration?
A: Typically 50-200 mM for biological applications. Higher concentrations increase capacity but may affect ionic strength.